The objective of this project is to understand the mechanism of the sodium-potassium pump. Our approach is to obtain information on the structure and molecular dynamics of the Na-K ATPase using fluorescence spectroscopy. Our studies will include a comparison between Na-K ATPases isolated from eel electroplax, various mammalian kidney sources and human red blood cells. We shall attempt to relate our spectroscopic findings to the various biochemical and transport functions of the enzyme.